Many existing wireless communication systems employ link adaptation to provide a suitable downlink from a Node-B to a WTRU. The WTRU measures channel quality based on a signal-to-interference (SIR) measurement, and then reports this measurement to the Node-B, enabling the Node-B to employ one or more optimized transmission parameters for communicating with the WTRU. These transmission parameters illustratively include the maximum data rate, minimum power, modulation type, or highest code rate that the WTRU can currently decode, given existing channel conditions. In some wireless systems, such as frequency division duplex (FDD) high speed downlink packet access (HSDPA) systems, these SIR measurements may be performed using a pilot transmission. Typically, such SIR measurements are conducted during channel estimation and subsequently utilized to estimate channel quality.
When a SIR measurement is conducted prior to demodulation, the performance of a demodulator in the receiver of the WTRU is not explicitly captured. Examples of such situations include SIR measurements that are provided by, or derived from, a channel estimation procedure. The underlying logic for basing SIR measurements on channel estimation is that a high quality channel should correspond to a high quality of reception. Unfortunately, this logic does not always hold true, especially when the quality of the receiver algorithm varies substantially.
A reception quality estimation procedure that accurately reflects receiver performance is desired, such that a better performing receiver will report better reception quality than a poorly performing receiver. Thus, more aggressive transmission parameters may be utilized in conjunction with the better performing receiver.